NORT: a non-oscillatory robust tuning approach for 2-DoF PI controllers

A tuning method for Two-Degree-of-Freedom (2-DoF) proportional integral (PI) controllers for First-Order-Plus-Dead-Time (FOPDT) models is presented. It allows the designer to deal with the closed-loop control system performance-robustness tradeoff specifying the required minimum robustness level selecting its maximum sensitivity in the 1.2 to 2.0 range. In addition, the performance is measured by forcing the closed-loop transfer functions to perform as close as possible to a target non-oscillatory dynamics. Controller tuning equations are provided for FOPDT models with normalized dead-times from 0.1 to 2.0. Examples show the effectiveness of the proposed tuning method.